As I understand it there is no "Learn More" page just a button: you give your e-mail, zip code and press the button.
You are correct. All of the variations would redirect to the home page regardless of what the button said.
So 10% look impressive.
Keep in mind that this is the percentage of people who volunteered at some point during the campaign after signing up on our splash page-- not the percentage of people who immediately decided to volunteer after signing up.